In U.S. Pat. No. 2,905,507 issued Sept. 22, 1959 to Harry C. May, and assigned to the assignee of the present invention, there is shown and described a self-lapping type of brake valve device that is automatically operative to effect, upon manually shifting a brake valve handle out of a release position and to a selected position in an application zone, a reduction of the pressure in an equalizing reservoir to a value corresponding to the position in the application zone to which the brake valve handle was shifted whereupon a relay valve device operated in response to this reduction of the pressure in the equalizing reservoir to effect a corresponding reduction of the pressure in a train brake pipe.
In recent years, there has been a slight reversion in brake equipment used in passenger and commuter service to the use of a brake valve device that is so constructed as to automatically charge a train brake pipe to a preselected chosen pressure, while the handle of this brake valve device occupies its release position, and require manual shifting of this handle in one direction to a service position to effect a reduction of pressure in the train brake pipe and thereafter shifting in an opposite direction to a lap position to terminate a reduction of the pressure in the brake pipe, since such a brake valve device is suitable to control the operation of car brake control valve devices of the direct release type which are capable of providing the necessary braking requirements for certain cars used in passenger and commuter service, it being understood that direct release brake control valve devices are less expensive than the graduated release type of brake control valve devices.
Brake valve devices that are substantially the same in construction and operation as the brake valve device shown and described in the above-mentioned U.S. Pat. No. 2,905,507 are presently manufactured and sold in large quantities whereas the manufacturing facilities for the mass production of the older heretofore used manually lapped brake valve devices are obsolete or have been discarded.
Accordingly, it is the general purpose of the present invention to provide a brake valve device that embodies a large number of the elements embodied in the presently manufactured self-lapping type of brake valve device with a minumum number of the elements of this brake valve device replaced by new elements which enable the provision of a brake valve device that is automatically operative to charge a train brake pipe to a preselected chosen pressure while its operating handle occupies a release position and manually lapped by movement of this handle from a service position to a lap position subsequent to its movement to the service position. It is readily apparent that such a modified brake valve device can be manufactured less expensively than the older types of manually lapped brake valve devices since these devices embodied therein a rotary valve and a valve seat each of which required a considerable amount of accurate machining that necessarily increased the cost of these brake valve devices.